Supersonic Fluidic Oscillator Pressure Control for Faster Superplastic Forming
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Solution Overview
Problem
Conventional superplastic blow forming processes are slow due to the inability of forming materials to achieve high elongation at high strain rates without tearing or cracking, limiting their application to high-value parts and requiring long manufacturing times for complex components.
Innovation Solution
The use of a bi-stable load switched supersonic fluidic oscillator (SFO) to regulate gas pressure within the forming chamber, maintaining a specific ratio of supply pressure to forming pressure to generate continuous, uninterrupted gas oscillations, enhancing deformation and stress relief of the material without moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional superplastic blow forming processes are used, then material elongation is maintained without tearing or cracking, but manufacturing time becomes excessively long (3-30 minutes for automotive parts, 45 minutes to 10 hours for aerospace components)
Solution Approach 1:
The patent applies periodic action by using a fluidic oscillator to generate oscillating gas pressure that cyclically loads and unloads the forming material. This periodic pressure variation allows the material to undergo high strain rate deformation during pressure peaks while stress relief occurs during pressure valleys, enabling faster forming speeds without causing tears or cracks that would normally occur at high strain rates.
Solution Approach 2:
The patent changes the pressure parameter dynamically by oscillating the gas pressure between maximum and minimum values during the forming process. This parameter change allows the system to achieve high strain rates during pressure peaks while maintaining material integrity through stress relief during pressure reductions, thereby increasing productivity without sacrificing material elongation capability.
2Productivity
If higher strain rates are applied to increase production speed, then manufacturing time is reduced, but the forming material develops tears or cracks due to inability to achieve high elongation
Solution Approach 1:
The fluidic oscillator generates periodic pressure variations that create cycles of high strain during pressure peaks and stress relief during pressure valleys. This periodic action allows the material to tolerate high strain rates without permanent damage, as the oscillating pressure provides repeated opportunities for stress relaxation, thereby maintaining material integrity while increasing production speed.
Solution Approach 2:
The system incorporates feedback through the fluidic oscillator's inherent pressure-sensing mechanism that automatically adjusts the oscillation based on the forming chamber pressure conditions. This feedback control ensures that pressure peaks do not exceed material tolerance limits while maintaining sufficiently high strain rates for improved productivity, thus preserving material integrity.
3Adaptability or versatility
If complex geometrically produced products are manufactured, then product versatility is improved, but manufacturing time increases significantly
Solution Approach 1:
The oscillating pressure from the fluidic oscillator enables complex geometric features to be formed more quickly by applying high strain rates during pressure peaks for difficult-to-form areas, while stress relief during pressure valleys prevents defects. This periodic loading pattern reduces the total time required to manufacture complex products compared to conventional steady-state pressure forming.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for higher strain rates and improved elongation, reducing manufacturing time and enabling the production of more complex geometrically produced products with enhanced deformation and stress relief.
Implementation Method 1
The use of a bi-stable load switched supersonic fluidic oscillator (SFO) to regulate gas pressure within the forming chamber, maintaining a specific ratio of supply pressure to forming pressure to generate continuous, uninterrupted gas oscillations
Data Source
AI summary
A method of controlling superplastic forming where a sheet of material is subjected to superplastic forming when in a chamber of a forming apparatus having a supersonic fluidic oscillator (SFO) includes determining maximum and minimum limits for a ratio of supply pressure applied to the SFO related to forming pressure, where the application of supply pressure to the SFO in a manner that maintains the ratio between the maximum and minimum limit causes the SFO to generate continuous, uninterrupted, gas oscillations; with a supply pressure sensor, detecting the gas pressure supplied to the SFO and transmitting it to a controller; with a forming pressure sensor, detecting the forming pressure within the chamber and transmitting it to the controller; and operating the controller to maintain the pressure supplied to the SFO to maintain the ratio of the detected supply pressure to the detected forming pressure between the maximum and minimum limits.